1. Field of the Invention
The invention relates to a device and a process for constructing a carcass and for preshaping the half-finished (unvulcanized) rubber tire.
2. Discussion of Background Information
The production of vehicle air tires in assembly stations by constructing the carcass package of a tire interior layer, carcass layers and bead cores is known. In another assembly station, the belt package is constructed independently thereof with breaker plies and, if necessary, bindings, treads, and lateral strips. The carcass package is transported to an airbagging machine for the tire shaping and centering. The belt package is also transported to the airbagging machine and positioned concentric to the carcass package in the axial position thereof. The carcass package is radially inflated in the airbagging device, receives the tire body shape, and is joined with the belt package radially from the inside. The carcass construction in this process takes place on an optimized, sealed construction surface of the build-up drum independently of the preshaping requirements. The preshaping takes place in the airbagging device, optimized for the preshaping and independent of the assembly requirements. However, a process of this type is very elaborate. It requires two different assembly stations for the carcass package and the belt package as well as an independent airbagging device for the tire shaping. Aside from the high number of structural elements and the space needed, the carcass package must be transported from the assembly station to the airbagging device. The carcass package can thereby be damaged and must then be centered once again on the airbagging device.
The construction of the carcass layers on a carcass build-up drum that is also constructed as an airbagging device is also known. In these known devices, the middle section of the build-up drum is directly constructed as an airbagging device. After constructing the carcass layers, the middle part of the build-up drum is itself radially expanded for the shaping of the tire so that the assembled carcass package is shaped and receives its body shape.
In order to achieve a roughly cylindrical surface for the construction of the carcass layers, an elaborate mechanism is required in embodiments of this type that causes the heavily segmented cylindrical surface making up the drum elements to follow the expansion. Since during the preshaping of the tire, the beading areas of the half-finished (unvulcanized) rubber tire must be axially moved together for the creation of a tire body shape, a significant mechanical and control effort (pneumatic, electric) must take place at the same time in order to remove the mechanical segments that previously made up the cylindrical construction surface from the middle area, so that the preshaping headers on which the bead cores are axially mounted can be pushed together in this area.
It is also known how to construct the contact surface in this axial area between both preshaping headers with a number of segments at larger distances from each other by which the spatial requirements for axially pushing together the preshaping headers is facilitated, but by which so many empty spaces exist for placement between the individual segments that the surface contour is severely compromised for the placement, whereby the quality of the uniform carcass construction is worsened. The construction surface must therefore accommodate the requirements of the preshaping, for example the ability to expand, at the cost of optimizing the surface for the assembly. The airbagging device becomes very elaborate since it must also satisfy assembly requirements. To make a change in the assembly contour, wide sections of the preshaping device must be replaced.